A common way of emptying sewage holding tanks on boats is to pump the sewage out of the holding tank using a dockside pump. In order to effectively practice this function it is important to have an air tight fit between the dockside pump out station and the boat waste deck fitting. In an attempt to facilitate this, the United States Coast Guard has promulgated regulations which require a 11/2 inch nominal internal pipe thread. However because exactly what a "11/2 inch nominal internal pipe thread" is cannot be clearly discerned from the regulations, it has been found--according to the invention--that three different deck fitting internal thread configurations are commonly provided on boats. It has also been determined according to the present invention that dockside pump out stations typically have one of two very different fittings, one which comprises a rubber (elastomeric material) right circular cone frustrum nozzle, and the other a fuel line type fitting, which is cam actuated, having a plurality of (typically two) curved locking surface locking cams.
While some adaptors presently exist to match the nozzle type dockside pump hose fittings, and others are available to match the cam actuated type, there are no universal adaptors. Requiring a marina to have pump out adaptors for every style of waste deck fitting is not practical, however if an adaptor were utilized on a boat which matched the waste deck fitting threads of that boat and was capable of air tight connection to the nozzle or cam actuated type of pump out hose fittings, practical pump out could be more universally effected. From the standpoint of the manufacturer of adaptors, this also would be practical since, according to the invention, it has been determined that only three different types of adaptors need be provided to accommodate the vast majority of deck fittings.
According to the a first aspect of the present invention, a pump out adaptor is provided. The adaptor comprises the following elements: A generally tubular body of rigid material, having a first end and a second end, with a through extending bore defining an axis substantially concentric with the first and second ends, and having an exterior and interior surface at the first end, and an exterior and interior surface at the second end. The interior surface of the first end defining a frustrum of a right circular cone, so that the bore at the first end has a gradually decreasing diameter from the first end toward the second end. The exterior surface of the second end having external screw threads. And, the exterior surface of the first end comprising a cylindrical surface with a semi-toroidal recess at a central axial portion thereof.
The external screw threads need only be one of three different types. One type has a nominal diameter of 11/4 inches and 111/2 threads per inch (in this case the nominal diameter including a major maximum diameter of 1.59 inches and a minor maximum diameter of 1.49 inches, and a maximum pitch diameter of about 1.55 inches). The second one has a 11/2 inch nominal diameter and 16 threads per inch (in this case a 11/4 inch nominal diameter comprising a major maximum diameter of about 1.62 inches, and a minor maximum diameter of about 1.56 inches, and a maximum pitch diameter of about 1.58 inches). The third has a 11/2 inch nominal diameter and 111/2 threads per inch (in this case a 11/2 inch nominal diameter meaning a major maximum diameter of about 1.88 inches, a minor maximum diameter of about 1.77 inches, and a maximum pitch diameter of about 1.82 inches).
The purpose of the semi-toroidal recess of the exterior surface of the first end of the adaptor is to cooperate with the curved surfaces of the locking cams on the fuel line type dockside pump hose fitting. Typically in order to do this the minimum diameter of the adaptor at the toroidal recess is about 1.7 inches, with the recess itself having a radius of about 0.3-0.6 inches. The purpose of the interior surface of the first end is to mate with the rubber nozzle type of dockside pump hose, and for this purpose the interior surface makes an angle of about 3.degree.-8.degree. (e.g. 51/2.degree.) with respect to the axis of the bore.
It is also desirable to provide a collar on the tubular body between the first and second ends thereof, which collar may have a plurality (e.g. three) of radially extending projections. At least one of the projections may have an opening in it, extending generally tangentially to the collar, such as for receipt of a clip or chain link so as to prevent ready removal of the adaptor from the deck fitting. Also a flexible sealing material (e.g. synthetic or natural rubber) annular ring may be provided between the collar and the external threads at the second end of the adaptor.
According to another aspect of the invention a system for connecting a dockside pump to a boat waste deck fitting to allow removal of waste from a boat sewage holding tank is provided. The system comprises the following elements: A dockside pump, connected by a hose to a fitting, the fitting selected from the group consisting essentially of an elastomeric material right circular cone frustrum, and a cam actuated fitting having a plurality of curved locking surface locking cams. A deck fitting on a boat connected to a sewage holding tank of the boat, the deck fitting having an internally threaded passage. And, an adaptor having first and second ends, and a through extending bore between the ends and substantially concentric therewith, the first end including means capable of positive sealed connection to both of the cone frustrum and locking cam fittings, and the second end comprising external screw threads cooperable with the deck fitting internally threaded passage.
According to yet another aspect of the present invention a method of efficiently pumping out sewage from a boat holding tank, the boat having a deck fitting with an internally threaded passageway, using a dockside pump connected to one end of a hose, which in turn is connected at another end thereof to a fitting, is provided. The method comprises the following steps: (a) Determining the two-five most common sizes for deck internally threaded passages. (b) Constructing two-five adaptors, each adaptor having a first end which can be connected with a positive seal to more than one type of dockside pump hose fitting, and a second end which cooperates with one of the common sizes of internally threaded passage, so as to provide one adaptor for each common size of deck internally threaded passage. (c) Attaching the second end of the appropriate one of the adaptors to a cooperating deck internally threaded passage. (d) Attaching the first end of the adaptor to a dockside pump hose fitting. And, (e) pumping the sewage out of the holding tank through the hose, dockside and deck fittings, and adaptor. In practicing the method the dockside pump hose fitting is typically selected from the group consisting essentially of an elastomeric material right circular cone frustrum, and a cam actuated fitting having a plurality of curved locking surface locking cams; and step (d) is practiced by inserting the right circular cone frustrum fitting into a right circular cone opening in the adaptor, or by bringing the locking cams into contact with cooperating recesses on an external portion of the adaptor.
It is the primary object of the present invention to provide for the practical adaptation of waste deck fittings to dockside pump hose fittings to facilitate the air tight suctioning of a boat holding tank contents off the boat. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.